How to Set Up an AI Agent Email Inbox in Minutes

You can stand up an AI agent email inbox on Mermail’s Free plan in a few minutes: console account → mailbox → MCP agent-inbox profile → first list_emails call. No SMTP, no custom domain required for the prototype.

What you will build

By the end of this guide you will have:

• A Mermail workspace with one Free mailbox
• An MCP connection using the agent-inbox profile (receive-first, no send)
• A confirmed agent loop: list mailboxes and list emails

Prerequisites

• A browser for the Mermail console
• An MCP-capable client: Cursor, Claude Code / Desktop, Codex, or similar
• Optional: a workspace API key (sk-proj-…) from Settings → API Keys if you prefer header auth over OAuth

Step 1 — Open the console and create an account

Go to https://console.mermail.app and sign up or sign in. Confirm you have at least one workspace. Free includes one inbox owned by you.

Step 2 — Create a mailbox

In the console, create a mailbox with a disposable or role-style username and a clear display name (for example, “Onboarding Agent”). Note the address and mailbox id — agents will use the id in tool calls.

You can also let the agent call create_mailbox after MCP is connected. Console-first is clearer the first time.

Step 3 — Connect MCP with the agent-inbox profile

Use the receive-first endpoint: https://console.mermail.app/mcp?profile=agent-inbox. Full catalog (includes send tools) is https://console.mermail.app/mcp — skip that until you explicitly need send.

# Claude Code
claude mcp add --transport http mermail-inbox \
  https://console.mermail.app/mcp?profile=agent-inbox

# Codex
codex mcp add mermail-inbox --url \
  https://console.mermail.app/mcp?profile=agent-inbox
codex mcp login mermail-inbox

{
  "mcpServers": {
    "mermail-agent-inbox": {
      "url": "https://console.mermail.app/mcp?profile=agent-inbox",
      "headers": { "x-api-key": "sk-proj-YOUR_KEY" }
    }
  }
}

Step 4 — Authenticate

Prefer OAuth 2.1 for interactive hosts. For headless or CI-style agents, set x-api-key to a workspace key with the sk-proj- prefix from Settings → API Keys.

Step 5 — Run the first agent loop

Give the agent a short prompt:

Using Mermail MCP (agent-inbox):
1. list_workspaces / list_mailboxes — confirm the Free mailbox.
2. list_emails on that mailbox (metadata-only is fine).
3. If empty, note the address and send yourself a test message,
   then list_emails again.
4. get_email on one id when you need the body.
Print mailbox ids and email ids as you go.

Agent-inbox exposes a focused allowlist (including create_mailbox, list_emails, search_emails, get_email) and does not expose send. Details: How to Use MCP with Mermail’s Email API.

Step 6 — Verify success

1. Mailbox appears in list_mailboxes
2. Test message shows in list_emails
3. get_email returns the body or context you expect
4. No send tools appear in tools/list for agent-inbox

What to do next

Need send or replies? Connect the default /mcp catalog with an authorized send workflow. Need branded addresses? Upgrade to Developer+ and follow Custom Domains for Thousands of Agent Inboxes. Product overview: mermail.app/agents.

Troubleshooting

• Auth fails. Regenerate sk-proj key; confirm header name is x-api-key.
• Empty inbox. Send a test message to the exact address; wait a moment; call list_emails again.
• Want send tools. You are on agent-inbox — switch URL deliberately to the full catalog.
• Need more than one inbox. Free is capped at 1 — see pricing for Developer (5 inboxes).

FAQ

How long does AI agent email inbox setup take?

Usually under 10 minutes if you already have an MCP client: account, mailbox, MCP URL, auth, first list_emails.

Does Free include MCP?

Yes. Free includes one mailbox and MCP access suitable for this tutorial.

Can I skip the console and only use MCP?

Yes after the account exists — create_mailbox works over agent-inbox. Console-first is easier for the first mailbox.